1. Key Laboratory of Biology and Genetic Resources of Tropical Crops, Ministry of Agriculture, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agriculture Sciences, Haikou 571101, P.R. China
2. Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, P.R. China
3. Department of Chemistry, Bielefeld University, 33615 Bielefeld, Germany